On 15 Aug 2018 10:13:53 GMT, dpb wrote:

Oh, from pictures one can't tell, the insulation doesn't _look_ hardened
but if that were so it would a be dead giveaway "Houston, we have a
problem"...

Thank you for noticing the blackened blue wires. It may have overheated at
some point as they do appear to be blackened a bit but the tinned copper
seems clean where it can be seen.
http://www.bild.me/bild.php?file=3775483test10.jpg

The side view shows that the two outside connections are the input (black)
power while the two inside connections (blue) are the output to the motor.
http://www.bild.me/bild.php?file=1169657flow04.jpg

I tested them all this morning and everything is as would be expected, so,
what I'm seeking now, is to re-create the conditions that cause the
intermittency, as there is no problem until that shows up (although the
bladder read 18 psi this morning (after the power to the booster was off
all night) which is 20 psi lower than I had expected.
http://www.bild.me/bild.php?file=6471227test07.jpg 18 psi tank

After I turned the power back on, bladder pressure rose to above 60 psi
http://www.bild.me/bild.php?file=8551539test09.jpg

As did the motor pressure gauge:
http://www.bild.me/bild.php?file=2732927test08.jpg